Venturi fan

ABSTRACT

A venturi-type fan is composed of a wire basket between front and rear flares. The wire basket has a rear portion to which the motor and fan blade assembly is mounted. The rear flare controls the admission of air into the fan to reduce turbulence and allows the flow of air to be accelerated and directed forward in a slowly diffusing column. The openness of the sides of the present fan reduces the noise generally associated with close-sided venturi fans without degrading air movement characteristics

CROSS REFERENCE TO RELATED PATENTS

The present application claims priority to U.S. Provisional ApplicationSer. No. 60/630,113, filed Nov. 22, 2004, incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to fans generally, and to fans used inindustrial and commercial settings in particular.

The purpose of a fan is move air in order to ventilate and cool an area.In industrial and commercial environments, where air conditioning may beimpractical, fans are vital to employees' health and comfort.

There are several types of fans used in commercial and industrialenvironments. One type includes a fan blade enclosed within a wire framehousing or “cage”, sometimes mounted on a pedestal. The shaft of a motoroutside the housing may project into the housing to turn the blades.These fans work fine in smaller quarters. Increasing the speed of themotor and the pitch of the blade allows this type of fan to throw moreair, but increases noise. Another type of fan is a venturi fan that hasa metal, venturi-shaped housing with a motor and a set of blades mountedtherein. The set of blades is rotated by the motor and thus acceleratesair through the housing. These fans move a large volume of air andproject it over large distances, which fact is especially important inlarge industrial buildings such as distribution centers, but they arerelatively noisy.

Thus there remains a need for improvements in fans, particularly highvolume industrial and commercial fans such as venturi fans.

SUMMARY OF THE INVENTION

According to its major aspects and briefly recited, the presentinvention is a venturi fan capable of producing a significant, directedflow of air but with significantly reduced noise compared to prior artventuri fans. The present fan has a body comprised of a generallycylindrical wire basket for carrying a motor and fan blade assembly, anda flared intake carried at the rear of the wire basket. Preferably, thefront of the basket carries an exit channel, which may also have a flarebut is otherwise preferably substantially cylindrical in shape. Therear-flared intake allows for a smooth feed of air into the basket andpast the motor and the air-accelerating fan blade assembly. The wirebasket, in a preferred embodiment, acts as a conduit for the flow-pathair but also admits additional air into the flow path and channels theflow of air produced by the fan while allowing fan noise to dissipatethrough the sides. The basket also avoids generation of some fan noiseand is a safety feature, preventing injury in its role as both the sideand rear finger guard.

An important feature of the present invention is the relatively opensides of the present fan, compared to prior art venturi fans. Therelatively open sides contribute significantly and in a number of waysto noise reduction, chiefly by allowing noise to escape, while notsignificantly degrading the flow of air. Indeed, the openness of thesides increases the amount of air available to the fan.

Additionally, the combination of the rear flare intake and the wirebasket is a significant feature of the present invention. Thiscombination allows the flow of air generated by the fan blade assemblyto be created and directed significant distances with little diffusion.

The use of the wire basket to support the motor and fan blade assemblyis yet another important feature of the present invention. Thisarrangement reduces material, weight and obstructions to air flow whileproviding a sufficiently sturdy securement for the motor and fan bladeassembly.

These and other features and their advantages will be apparent to thoseskilled in the art of fan design from a careful reading of the DetailedDescription of Preferred Embodiments accompanied by the followingdrawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings,

FIG. 1 is a perspective view of a fan, according to a preferredembodiment of the present invention;

FIG. 2 is a side view of the fan of FIG. 1, according to a preferredembodiment of the present invention;

FIG. 3 is a front view of the fan of FIG. 1;

FIG. 4 is a rear view of the Fan of FIG. 1;

FIG. 5 is a perspective view of the Fan of FIG. 1 with the front fingerguard and fan blade assembly removed to show the mounting of the motor;and

FIG. 6 is a detailed view of the interior of the fan of FIG. 2 showingthe manner in which the motor is mounted, according to a preferredembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is an improvement in venturi-style fans. Venturifans direct a significant quantity of air in a forward direction and aresuitable for large buildings such as warehouses. Unfortunately, priorart venturi fans are relatively noisy.

FIG. 1 illustrates in perspective the present venturi fan 10. Fan 10 hasa housing 12 that is flared on both the front 14 and the rear 16, andhas a front finger guard 18. Inside housing 12 is a motor 22 and a fanblade assembly 24.

Referring now to FIG. 2, there is illustrated a side view of venturi fan10 according to a preferred embodiment of the present invention. Fan 10is rotationally symmetric so it appears the same from all sides. Unlikeprior art venturi fans, venturi fan 10, shown in FIGS. 1-6 in itspreferred embodiment, has an opening formed in the side wall 28,preferably a multiplicity of openings such as perforations or an arrayof slots, but, most preferably, a multiplicity of openings formed byspacing wires 34, either by constructing a cage or basket 32, as shown.Basket 32 is illustrated as made from circular wires 34 secured at thedesired intervals with cross supports 36, also made of wire, or,alternatively, by forming a single helical wire secured with crosssupports to maintain the desired spacing of each turn of the helicalwire. Spacing between adjacent wires is in part dictated by safetyrequirements imposed by authorities, by the requisite strength requiredfor fan 10, by the function of fan 10 to serve as an airflow conduit butotherwise fan 10 is preferably open on side 26 to the greatest extentpossible.

Safety requirements relate to the size of the openings between wires 34that, when properly set, the likelihood that someone will inadvertentlystick fingers into the interior of basket 32 in the vicinity of fanblade assembly 40 is minimized. Consequently, the spacing will take intoaccount the age of those likely to come into contact with fan 10 and theproximity of fan blade assembly 24 to basket 32. Thus, the spacing willbe wider if wires 34 are farther from fan blade assembly 24 and narrowercloser to fan blade assembly 24, and can include both spacings in thesame basket 32, as best seen in FIG. 2.

Basket 32 must also be rigid enough to support fan blade assembly 24, amotor 22 and a rear flare 16. Rear flare 16 is the solid portion ofhousing 12. The term “flare” simply means that the cross sectional areataken at right angles with respect to the direction of air flowincreases toward the end of housing 12, as in the flare of a trumpet.Optionally, front flare 14 is added to fan 10 to give the present fan 10a symmetric, finished look. Front flare 14 includes an optional frontfinger guard 18, best seen in FIG. 3. Basket 32 is made to bebasket-shaped so that it's rear portion 50 contiguous with side wall 28and best seen in FIG. 5, acts as a finger guard for the rear of fan 10.

Rear flare 16 helps to control the flow of air into fan 10 is because itminimizes turbulence and increases laminar flow. Rear flare 16 issignificant from an airflow standpoint; front flare 14 is much less soand is essentially an optional feature of the invention, providedessentially for appearances.

In addition to acting as a rear finger guard, rear portion 50 provides asurface on which motor 22 can be mounted. Rear portion 50 has a centralopening through which motor 22 is partially inserted. Brackets 54, thatrun along the side of basket 32 across rear portion 50 and thence intothe interior of basket 32 where they form loops 58 and then return, areused to support motor 22. Threaded posts 60 on the front of motor 22extend through loops 58. Nuts 62 are then threaded to posts 60 to securemotor 22 to brackets 54.

Motor 42 has a central shaft 68 to which fan blade assembly 40 isattached. Blade assembly may have three or more paddle blades 70.

The present fan 10 is much quieter than prior art venturi fans. Whilenot wishing to be bound by theory, it is believed that this result hasbeen achieved by a number of different factors working in combination.First, although fan 10 controls and directs airflow in much the same wayas a prior art venturi fan, sound now can disperse over a greater anglebecause side wall 28 of fan 10 is open and is not channeled with theairflow. Second, in the prior art venturi fan, the tips of its bladeassembly normally pass closer to the housing than in the present fan 10and the turbulence that arises sets up vibrations in the solid housing.Those vibrations are reflected throughout the housing and may resonate.Turbulence is reduced in the present fan 10. Indeed, the tips of fanblade assembly 24 are farther from wires 34 at least for safety reasonsalone, and are no longer as starved for air, as air is admitted freelythrough side wall 28 between wires 34. Furthermore, vibrations createdby the movement of fan blade assembly 24 in the vicinity of wires 34 areweaker and less easily reflected by wires 34. The prior art side wallmounted bracket has been removed in favor of mounting motor 22 directlyonto rear portion 50, thus eliminating a structure on the interior ofthe fan that causes additional turbulence and noise. It is believed thatthese changes result in less noise and “whiter” noise, that is, noisespread more evenly over the audible frequency spectrum.

The shapes of the front and rear flares 14, 16 may be the same and maybe symmetrical with respect to each other, but may alternatively bedifferent if desired for packaging efficiency. For example, rear flare16 may have a smaller diameter where it fits onto basket 32 than frontflare 14 in order that basket 32 may have a slightly frustoconicalshape, as shown best in FIG. 2, so that it nests better with otherbaskets 32 in shipping or storing.

Many modifications and substitutions will be apparent to those skilledin the art of fan manufacture from the foregoing description of thepreferred embodiments without departing from the spirit or scope of thepresent invention. It is intended that the scope of the presentinvention include all modifications that incorporate its principaldesign features, and that the scope and limitations of the presentinvention are to be determined by the appended claims.

1. A fan, comprising: a motor having a shaft; a fan blade assembly carried by said shaft and rotatable therewith when said motor is operating, said fan blade assembly forming a flow of air when rotating; and a housing having a rear flare, a side wall having at least one hole formed therein to admit air through said side wall to join said flow of air when said fan blade assembly rotates, and a rear portion for carrying said motor.
 2. The fan as recited in claim 1, wherein said at least one hole is a multiplicity of holes.
 3. The fan as recited in claim 1, wherein said side wall is formed of spaced apart wires.
 4. The fan as recited in claim 1, wherein said side wall and said rear portion are formed of a wire basket.
 5. The fan as recited in claim 1, wherein said side wall is formed of a helical wire having plural turns, each turn of said plural turns being spaced apart from adjacent turns of said helical wire
 6. The fan as recited in claim 1, wherein said side wall is frustoconically shaped.
 7. The fan as recited in claim 4, wherein said wire basket is frustoconically shaped.
 8. The fan as recited in claim 1, wherein said housing carries a front finger guard.
 9. The fan as recited in claim 1, wherein said rear portion surrounds said motor.
 10. The fan as recited in claim 1, further comprising means carried by said rear portion for mounting said motor.
 11. The fan as recited in claim 10, wherein said mounting means is a set of brackets. 